If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

NEMA twist lock plugs & receptacles

11-11-2012, 01:32 PM

Can anyone tell me if an L6-20P (3 wire, 20 amp) plug will plug into an L6-30R (3 wire, 30 amp) receptacle? The service to my welding area is 30 amps and therefore I should use a 30 amp receptacle. However, my Hypertherm Powermax 30 has the 20 amp plug. My Hobart HH180 and Dynasty 200 both draw 20 amps max at 240V so I could use either a 20 or 30 amp plug on them. I am trying to standardize my plugs and eliminate the need for adapters, jumpers, cheaters etc.

The L6-20 will not work with the L6-30R. You will not be able to make them work together without a cheater cord. Which is still not recommended since their is an extra 10 amps of potential disaster to the electronics you are plugging into using the L6-30R. You can make a Cheater cord with a 20Amp breaker in it to protect the electronics.

Do a search for Nema twist lock plugs and you can see diagrams that show the difference.

Comment

I have been looking at so many NEMA diagrams that I can no longer see straight. Unfortunately I have not found any with DIMENSIONS. The L6-20P and L6-30P LOOK the same in the diagrams. I do not know if the diameter described by the blades is the same or different. I guess I will go to the local electrical supply store next week and see what they have in stock and see what fits into what.

Regarding the fusing of the circuit, it is my understanding that the fuses (or breakers in my case) are intended to protect the line from the breaker or fuse panel to the outlet, not the device itself. The Dynasty 200 manual recommends 30 amp fuses for a 230 volt single phase hookup. The machine is designed to draw 20 amps at max output. I suspect that 20 amp fuses would tend to blow frequently due to short term fluctuation in current draw.

I hate the NEMA 6-50 "welder" plugs. The molded ones are not too bad but the "wire them yourself" plugs ones are huge and clunky and the receptacles even worse. I hope I can get this twist lock business sorted.

Regards,

Ken

Comment

Update... I found on evilbay what appears to be a photo of a collection of twistlock sockets. The L6-30 does appear to have the blades on a larger diameter circle than an L6-20. So I guess that confirms TerryL's information.

Ken

p.s. I also learned on evilbay that if I use an L6-30 socket I could plug in a Nissan Leaf electric vehicle. Or, put another way, If I found someone with a Nissan Leaf I could plug my welder into their charging station

Comment

My experience with twist lock connectors is limited to the one I have on my generator. In looking at all the diagrams I was suspecting the the "L6" in the designation had to do with a family of plugs/receptacles. Perhaps it does but no in the way I first thought.

I think for now I will use the L6-30 on the Dynasty and for the outlet which I use for the Dynasty. The other outlet, in the garage, I will leave as a "welder" plug. I can then use the HH180 or the Powermax there. If I need to use the Dynasty outside I will have to build a "welder" plug to L6-30 adapter.

Ken

Comment

Can anyone tell me if an L6-20P (3 wire, 20 amp) plug will plug into an L6-30R (3 wire, 30 amp) receptacle? The service to my welding area is 30 amps and therefore I should use a 30 amp receptacle. However, my Hypertherm Powermax 30 has the 20 amp plug. My Hobart HH180 and Dynasty 200 both draw 20 amps max at 240V so I could use either a 20 or 30 amp plug on them. I am trying to standardize my plugs and eliminate the need for adapters, jumpers, cheaters etc.

TIA,

Ken

That is incorrect- they are RATED @ 20amps but will pull more amps at "max".

Anyhoo-
Just change all you connectors to L6-30- if that is what you have as a receptacle in the wall- it will be safe for the machines you have.

Comment

Perhaps RATED was the wrong term. the specifications table for the Dynasty shows 20.0 "Amperes Input at Rated Output" as the highest for 230 volt single phase operation. Same for the Hobart.

Further investigation shows that the physical dimensions of the L6-20 and L6-30 "plugs" are the same so I would not save any space with the 20 amp. Good SJOOW 10/3 cable is not that much more than 12/3 considering I only need about 20 feet for my hookup.

Bottom line, I agree with your bottom line - I will just go with L6-30 and 10/3 and be done with it.

Comment

Perhaps RATED was the wrong term. the specifications table for the Dynasty shows 20.0 "Amperes Input at Rated Output" as the highest for 230 volt single phase operation. Same for the Hobart.

Further investigation shows that the physical dimensions of the L6-20 and L6-30 "plugs" are the same so I would not save any space with the 20 amp. Good SJOOW 10/3 cable is not that much more than 12/3 considering I only need about 20 feet for my hookup.

Bottom line, I agree with your bottom line - I will just go with L6-30 and 10/3 and be done with it.

Ken

???
Rated is the correct term:
as you mentioned- the manual only gives you amps at RATED Welding output